Method for switching consumer on or off

ABSTRACT

A method for turning various classes of loads on and off by means of switch elements in the context of energy management performed by a control unit, particularly in a motor vehicle, is described, in which the triggering of the switch elements is done such that the selected priorities for triggering the switch elements can be varied during operation, that is, dynamically. This enables an adaptation of the switching priorities during ongoing operation as a function of the operating state. The turn-off of loads is done by varying the switching priority in such a way that the perceptibility of the operating states is suppressed as much as possible, and the priorities can also be varied in accordance with person-specific criteria.

BACKGROUND OF THE INVENTION

In the on-board electrical system of motor vehicles, the electricalloads are grouped in various classes. There are loads that areabsolutely necessary for safe operation and the safety of the vehicle,such as the running lights, engine or other control units, fuel pumps,and so forth. These loads will hereinafter be called “non-controllableloads” (NSVs).

There are also electrical loads where the driver notices immediately orvery quickly that they are turned on or off, such as a passengercompartment fan, radio, seat adjuster, windshield defroster, and soforth. These loads will hereinafter be called “conditionallycontrollable loads” (BSV).

Finally, there are loads that have storage behavior, so that aninterruption in the supply of energy or the turning off of the voltagesupplying them is not noticed until after a certain period of time.Examples of such loads are a seat heater, rear window defroster,electric supplementary heaters, the cigarette lighter, and so forth.These loads will be called “controllable loads” (SVs). The goal of anenergy management system (EM) is to switch the controllable loads, andunder certain conditions the conditionally controllable loads BSVs, insuch a way that the battery state is or becomes favorable. In addition,with the aid of the energy management (EM), better coupling of the drivetrain and on-board electrical system should be possible, for instance inorder to achieve such functions as drive train relief by deexcitation ofthe generator during acceleration, or an additionally operative drivetrain loading during braking by full excitation of the generator.

From German. Patent Disclosure DE-OS 39 36 638, a method is alreadyknown in which the loads in a vehicle on-board electrical system areturned off or switched back if a certain load state of the vehiclebattery is undershot, so as to prevent the battery from discharging toomuch. Which load or loads is or will be turned off depends on what groupof loads it belongs to. One such group is composed for instance of“conditionally switchable loads” (BSVs) and/or “switchable loads” (SVs).The group is always turned off completely or reduced in terms ofconsumption. Several groups that contain “BSVs” and/or “SVs” aredefined. Each group has a priority pertaining to vehicle safety or tothe importance of the group. Turning off or resetting of the individualgroups begins with the group having the lowest priority. If this doesnot improve the charge state of the battery, then further groups areturned off or switched back, until the battery load state reaches acertain level.

In addition, from European Patent Disclosure EP 0 601 300 B1, a methodis known in which the resetting or turning off of the electric loads inan on-board vehicle electrical system is dependent on the driving state.The driving states pertain to the vehicle speed and stopping on the onehand and the operating state of the internal combustion engine on theother. On the basis of the signals are information furnished by sensors,a control unit of the vehicle can depend, depending on the vehicle stateinvolved, which types of loads should be turned off or switched backeither individually or in groups, simultaneously or in succession inaccordance with a predetermined order.

In the above-described methods, only energy economy and maintainingoperating and vehicle safety are taken into account. The perceptibilityof the operating states, such as a decrease in heating output of theseat heater or other loads to be turned off or reset, is not taken intoaccount since the loads are switched in accordance with a predeterminedstrategy that is invariable, rather than in accordance with their state.

SUMMARY OF THE INVENTION

The object of the invention is to adapt the switching strategy orprioritizing of the loads even during operation in such a way that theperceptibility of the operating states caused by the switchover isjointly taken into account, and the ndividual adaptation to specifiablecriteria is effected, thus overcoming the disadvantages of the priorart. This object is attained by a method of the invention.

The method according to the invention has the advantage that the effectson comfort that can be caused under certain operating conditions by theenergy management are reduced or suppressed entirely in terms of beingperceptible and thus are not noticed by the vehicle passengers.

This advantage is attained by performing dynamic prioritizing of theload power; that is, a change in priority can optionally be done undercertain circumstances even during operation. By measuring or estimatingthe operating states of the loads, the loads are assigned priorities asa function of the operating state. In accordance with these priorities,initially only loads of the “switchable load” priority are switched, andonly until the power deficit is compensated for. Only if that no longersuffices are loads of the “conditionally switchable load” class switched(turned off). This assures that the switching of the loads remainsunnoticed (neutral in terms of comfort) by the passengers for as long aspossible.

Further advantages of the invention are attained by the provisionsrecited in the dependent claims. These provisions make it possible forinstance for individual loads to change their assigned classes, and thischange is advantageously made as a function of time and/or of detectedoperating states. It is especially advantageous that individual loadscan be equipped with a certain intelligence that makes it possible forthem to assign themselves to the appropriate class, as a function oftheir operating state.

The prioritizing of the electric loads can advantageously be donevehicle- and/or person-specifically. Aspects of the future driving cyclecan be taken into account and the energy management strategy thusinfluenced. In suitable equipped vehicles with a navigation system, theinformation provided by it can also be taken into account in setting theswitching priorities. With the aid of learning systems (memoryfunctions), the driver can be recognized and the individual drivingbehavior or individual load activation or comfort preferences of theparticular driver can be ascertained and stored in memory and taken intoaccount on future trips, especially in recurring driving cycles.

The energy management extends advantageously not merely to switchingelectric loads but also includes mechanical components that can beturned on or off in order to achieve a desired effect, such as rpmadaptation or load optimization. The energy management is advantageouslyperformed by means of a control unit, such as an on-board electricalsystem control unit.

BRIEF DESCRIPTION OF THE DRAWINGS

One exemplary embodiment of the invention is shown in the drawing andwill be described in further detail below. The sole drawing FIGUREschematically shows the components of an on-board vehicle electricalsystem that are essential to comprehension of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention will now be described in terms of the exemplary embodimentshown in the drawing. However, it is not limited to an on-boardelectrical system for a vehicle but instead in general includes systemsin which loads are switched as a function of the operating state.

In the drawing, the components of an on-board vehicle electrical systemthat are required for comprehension of the invention are shownschematically. The electrical energy for the various electrical loads isfurnished by the generator G, which is driven by the engine, not shown.Via the generator terminal B+, the output voltage of the generator UB+is delivered to the battery B with the ignition switch Z closed.

Of the loads, the “switchable loads” (SVs), “conditionally switchableloads” BSVs , and the “non-switchable loads” NSVs are shown, which canbe connected to the battery B via switches S1, S2 and S3 that aretriggerable by a control unit SG. The switch S3 remains closed when theengine is in operation. The switches S1, S2 and S3 can also each includea plurality of individually triggerable single switches.

The control unit SG, for instance an engine control unit or an on-boardelectrical system control unit, as the energy manager, performs theenergy management EM. To that end, the control unit SG is supplied withthe requisite information for detecting the existing operating statesvia inputs El, E2, . . . . Via outputs A1, A2 and A3, the switches S1,S2 are actuated, and optionally S3 as well upon turn-off, and theassociated loads are turned on and off in accordance with the criteriaascertained in the control unit SG. Via further outputs A4, A5, A6, . .. , the control unit performs further triggering provisions that bringabout engine control and/or turn mechanical loads MV on and off. Onesuch mechanical load is an air conditioner compressor, for instance,which can be considered to be a “switchable load” SV and can be switchedas a current load in its electrical action and also as a mechanicalload, and which can be turned off, for instance in an acceleration phasein order to turn of the braking action. This also applies to thegenerator, which can be at least partly deexcited upon acceleration.

1. Classification of the Loads

The individual loads, both the electrical and the mechanical ones, areclassified in individual classes. Classified in the class of“non-switchable loads” (NSVs), which for instance include the runninglights, engine controller or control unit, fuel pump, and a mechanicalpump for the power steering, etc.; the class “conditionally switchableloads” (BSVs), which include for instance the heater fan, the radio, aseat adjuster or the windshield defroster, etc., and the class“switchable loads” (SVs), which include for instance a seat heater, rearwindow defroster, electrical supplementary heater, the cigarettelighter, and the mechanical air conditioner compressor.

The NSV class includes loads that are absolutely necessary for safemovement of the vehicle. They cannot be turned off or reset. This classaccordingly has the highest priority. Loads that can be turned off orreset but whose turn-off or resetting is noticed immediately or veryquickly by the driver or whose function improves vehicle control belongto the BSV class. It accordingly has a lower priority than the NSVclass. The class SV contains loads with storage behavior, whose shutoffor resetting to interrupt the energy supply is not noticed immediatelyby the driver but only after a specifiable period of time. Thus it hasthe lowest priority.

The grouping of the individual loads into priority classes is shown inTable 1, for instance. This grouping of priorities shown pertains to thenormal state.

2. Changing of the Classes

This grouping of individual loads into the various classes, as givenabove in the this section by example, pertains as already noted to thenormal state. The normal state exists when an adequate energy supplyduring typical driving operation is assured. If there is a change ofstate, the individual load cannot enter a class of lower priority thanthe class to which it belongs when it is in the normal state. However,as a function of its applicable operating state, it can enter a class ofhigher priority. In Table 2, an example in which a change of priorityoccurs is shown.

In the example in Table 2, the seat heaters are turned off and on againin alternation, and are thus shifted in alternation from the SV class toBSV and back again. The following scenario is assumed: The passenger anddriver have each turned on the seat heater, and the final temperaturehas been reached. This creates a power deficit at time T1, which isdetected by the energy management EM and which can be compensated for byturning off one seat heater. At time T2, the seat heater 2 is turnedoff. As a result, the seat heater 2 will change its priority in thedirection of BSV. At time T3, the seat heater 2 has cooled down enoughthat the passenger would notice any further cooling. The result is thechange of the seat heater to class BSV. The seat heater 2 now has ahigher priority than the seat heater 1. At time T4, the seat heater 2 istherefore turned back on again, while the seat heater 1 is turned off.At time T5, the seat heater 2 has warmed up again enough that it can beput back into class SV. The energy saving, on the precondition that theenergy suffices for heating at lower power, thus remains unnoticed bythe vehicle passengers.

3. Assignment to Classes

The assignment of the loads to the applicable class can be done invarious ways. One conceivable way is for an overriding system to detector estimate the operating state of the applicable consumer on the basisof the signals furnished by sensors or by an observer, the signals beingsupplied to the control unit SG, which performs the energy management,via the inputs E1, E2, . . . , and thus the overriding system makes thechange in the classification if necessary. The change in classmembership can also be made after a certain length of ON or OFF time. Itis also conceivable that the load may have intelligence and include amicroprocessor, for instance, so that it performs its assignment to theappropriate class on its own, as a function of its operating state.

Mechanical Loads

The assignment to classes is not limited to electrical loads only butalso applies to mechanical loads. This makes it possible to expand thefunctions of the energy management EM. For instance, the assignment of amechanical air conditioner compressor (in the normal state) to the classSV can be utilized to turn the compressor off during an accelerationphase of the motor vehicle, in order to have more power available forpropelling the vehicle. It is also conceivable to take the mechanicalcoupling of the generator to the drive train into account, in order todeexcite the generator during acceleration and excite it fully in atargeted way during braking. In vehicles that have a starter generatorconnected directly to the crankshaft, acceleration and braking effectscan thus be attained especially effectively, and mechanical energy canalso be converted back into electrical energy during braking.

The prioritizing of the loads can fundamentally be donevehicle-specifically or also person-specifically, especially takingspecial comfort preferences into account. The priorities for switchingloads are thus not the same for all vehicles of one model series butinstead vary as a function of the person, which applies to both turningloads on and turning them off.

In addition, aspects relating to the future driving cycle can be givenor taken into account and the energy management strategy can thus beoptimized. Provisions for increasing the power production or reducingpower consumption, which have effects on fuel consumption or thefunction and/or comfort, can be employed in a targeted way.

By memory functions in the area of seat position, mirror adjustment, andso forth, and/or other functions of driver recognition, such as accesscontrol, passive entry, fingerprints, and so forth, the driver of thevehicle is known to the control unit, which can react to this. With theaid of learning systems, the individual driving behavior or individualload activations (comfort preferences) of the particular driver can beascertained, stored in memory, and taken into account in the energymanagement. Furthermore, a certain recurring driving cycle, such as thedaily commute to work, can often also be associated with the driver.

By taking these traits into account, it is possible to prioritize theloads in a person-specific way. If comfort is important to one driver,which can be detected from the comfort loads he turns on in the normalstate, then the priority of the comfort loads should be raised to aboveaverage. A reduction in comfort by turning off comfort relevant loads toimprove a critical load balance should be avoided as much as possible inthis case. In that case, other provisions can be taken to improve theload balance, and for instance an adaptation of the rpm level foroptimal electric power generation should be preferred. For a driver whoplaces less value on comfort but more on driving in a way favorable tolow fuel consumption, conversely, comfort loads would more likely beturned off. A change (increase) in the rpm level, which increases fuelconsumption, should conversely be avoided as much as possible.

If after a relatively long period of observation or learning phase, acertain driving cycle and thus the rpm level can be assigned to aspecific person, then the limits of intervention for improving the loadbalance can be estimated better. That is, if a critical load state isdetected, but a favorable driving cycle for electric power generationcan be expected in the near future with a certain statistical certainty,then no provisions for raising the load balance have to be initiated.Such provisions are always associated with increased fuel consumptionand/or a loss of functionality or comfort and should therefore beavoided if possible. However, this is not true if a breakdown in theelectrical power supply is about to happen; then, provisions thatprevent this must be taken.

All in all, the embodiments described involve methods that change thepriorities of the loads as a function of their state. The switching ofthe loads depends on their priority. The priorities of the loads aredefined in software, in accordance with the following relationship:

Switching-state=f(priority)

Priority=f(state of the load)

The switching is done not class by class but rather in such a way thatindividual loads of one class are switched. The switching is done eithersuccessively, in adaptation to the load state, or parallel, if aplurality of loads have to be switched for compensation purposes, or theentire class if necessary. It is always the loads with the lowestpriority that are switched first, and only after all the loads with thelowest priority have been switched as loads with the next higherpriority switched (turned off).

TABLE 1 Classification of the Loads in Groups by Priority (Example) NVSBSV SV Running lights Heater fan Seat heater Engine control Radio Rearwindow defroster unit Fuel pump Seat Electric supplementary adjusterheater Etc. Windshield Cigarette lighter defroster Etc. Etc.

The classification of the priorities shown pertains to the normal state.

TABLE 2 An Example of Changing the Membership and Priority Groups TimeAction BSV SV T1 (EM detects power Seat heater 1 (ON) power deficit)(ON) Seat heater 2 T2 (EM turns seat Seat heater 1 (ON) heater 1 off)(OFF) ← Seat heater 2 T3 (Heater 2 changes Seat heater 1 (ON) priority)Seat heater 2 (OFF) T4 (EM switches Seat heater 1 (OFF) heater 2 ON Seatheater and heater 1 OFF) 2 (ON) → T5 (Priority of Seat heater 1 (OFF)heater 2 drops back) ← Seat heater 2 (ON)

What is claimed is:
 1. A method for turning on or off electrical loadsin a vehicle on-board electrical system, by means of switch elementswhich are triggerable in such a way by a controller that the electricalloads are turned on or off taking switching priorities into account,characterized in that the electrical loads are grouped in classes ofdifferent switching priorities and the grouping of the electrical loadsis done based on a normal state, the grouping of the electrical loads inclasses with the switching priorities is variable dynamically duringoperation as a function of the operating state of the electrical loads,and the electrical loads can change their class belonging during theoperation, wherein the switching of loads is performed by a control unit(SG) of a vehicle, and the loads are electrical and optionally alsomechanical loads whose switching priority is varied by the control unitin accordance with the specifiable conditions, and wherein in the choiceof priorities of the loads, drive requirements are taken into account,so that a driver-dependent turn-on or turn-off of the loads takes place.2. The method for switching loads of claim 1, characterized in that theloads are turned on or off as a function of priority, and the loads withthe lowest priority at a given time are turned off first and turned onagain last.
 3. The method for switching loads of claim 1, characterizedin that the loads are subdivided into the priority classes of“non-switchable loads” (NSV), “conditionally switchable loads” (BSV),and “switchable loads” (SV), with different switching priorities, withthe priority decreasing in the order given.
 4. The method for switchingloads of claim 1, characterized in that the driver is recognized by thecontrol unit (SG) by the evaluation of specifiable conditions thatcharacterize the driver.
 5. The method for switching loads of one of theforegoing claims, characterized in that the priorities are adapted insuch a way that the perceptibility of the operating states is minimized,and in particular in the case of a seat heater, the switching prioritiesare adapted such that the intermittent turn-off is not perceived.
 6. Amethod for turning on or off electrical loads in a vehicle on-boardelectrical system, by means of switch elements which are triggerable insuch a way by a controller that the electrical loads are turned on oroff taking switching priorities into account, characterized in that theelectrical loads are grouped in classes of different switchingpriorities and the grouping of the electrical loads is done based on anormal state, the grouping of the electrical loads in classes with theswitching priorities is variable dynamically during operation as afunction of the operating state of the electrical loads, and theelectrical loads can change their class belonging during the operation,wherein the switching of loads is performed by a control unit (SG) of avehicle, and the loads are electrical and optionally also mechanicalloads whose switching priority is varied by the control unit inaccordance with the specifiable conditions, wherein in the choice ofpriorities of the loads, requirements of the on-board electrical systemand/or of the drive train of the motor vehicle are taken into account,and wherein specifiable traits and preferences or habits of the driverand/or typical travel routes are recognized by the control unit (SG) andstored in memory and are also taken into account in the setting of theswitching priorities.
 7. A method for turning on or off electrical loadsin a vehicle on-board electrical system, by means of switch elementswhich are triggerable in such a way by a controller that the electricalloads are turned on or off taking switching priorities into account,characterized in that the electrical loads are grouped in classes ofdifferent switching priorities and the grouping of the electrical loadsis done based on a normal state, the grouping of the electrical loads inclasses with the switching priorities is variable dynamically duringoperation as a function of the operating state of the electrical loads,and the electrical loads can change their class belonging during theoperation, wherein in the choice of priorities of the loads, driverrequirements are taken into account, so that a driver-dependent turn-onor turn-off of the loads takes place.
 8. The method for switching loadsof claim 7, characterized in that the driver is recognized by thecontrol unit (SG) by the evaluation of specifiable conditions thatcharacterize the driver.
 9. A method for turning on or off electricalloads in a vehicle on-board electrical system, by means of switchelements which are triggerable in such a way by a controller that theelectrical loads are turned on or off taking switching priorities intoaccount, characterized in that the electrical loads are grouped inclasses of different switching priorities and the grouping of theelectrical loads is done based on a normal state, the grouping of theelectrical loads in classes with the switching priorities is variabledynamically during operation as a function of the operating state of theelectrical loads, and the electrical loads can change their classbelonging during the operation, wherein specifiable traits andpreferences or habits of the driver and/or typical travel routes arerecognized by the control unit (SG) and stored in memory and are alsotaken into account in the setting of the switching priorities.